1. Field of the Invention
The present invention relates to an aqueous glittering ink which can be suitably used for writing tools, printing inks, fields pertaining to coatings, cosmetics, and the like.
2. Description of the Prior Art
Heretofore, for the purpose of obtaining written marks with metallic luster such as gold and silver, aqueous ink using glittering pigments have been proposed. For example, Japanese Unexamined Patent Publication Hei 7-118592 proposes an aqueous ink using an aluminum powder pigment. Japanese Unexamined Patent Publication Hei 8-151547 proposes an ink using a pearlescent pigment. Japanese Unexamined Patent Publication Hei 11-29734 proposes an aqueous metallic ink prepared by coloring an aluminum powder with an organic pigment fixed.
However, in the case of such conventional aqueous inks using glittering pigments such as aluminum powder pigment, pearlescent pigment and the like, it has been difficult to obtain written marks or coated films with strong glittering feeling and spatial effect. Moreover, although in order to obtain, in particular, colored metallic color, a method has been adopted in which these glittering pigment particles are colored with coloring materials such as dyes and pigments, there has been a problem that the glittering feeling is lost despite the improvement in color development.
As a result of intensive studies for achieving the said objects, the present inventors have adopted an aqueous glittering ink containing scaly glittering particles, a water-soluble resin, a water-soluble organic solvent, a colorant and water, wherein the said scaly glittering particles have a median diameter of at least 10 xcexcm, a ratio of smoothness on the particle surface to a median diameter of not greater than 0.011, and a surface coating ratio of the said colorant on the said particle surface of not greater than 80% in a state of dried written marks.
By adopting the said constituents, written marks or coated films can be obtained with a strong glittering feeling and a spatial effect, as well as a good color development compared with the aqueous ink using the conventional glittering pigments.
In particular, as a preferred embodiment of this invention, in addition to the above-mentioned constituents, it is desirable to use an aqueous ink having the pseudo-plasticity fluidity (thixotropic property), preferably an aqueous ink having the said thixotropy index (T.I. value) of not less than 1.3 represented by the ratio of V0.5 to V1.0 (V0.5/V1.0), wherein V0.5 is the viscosity with the rotation speed of 0.5 rpm and V1.0 is the viscosity with the rotation speed of 1.0 rpm when the ink is measured by an ELD-typed viscometer (3xc2x0 R14 cone, at the temperature of 20xc2x0 C.), more preferably an aqueous ink having the pseudo-plasticity fluidity (thixotropic property) with V0.5 of 1000xcx9c15000 mPaxc2x7s, preferably 1000xcx9c10000 mPaxc2x7s, the viscosity when measured by an ELD-typed viscometer with a rotation speed of 0.5 rpm(3xc2x0 R14 cone at the temperature of 20xc2x0 C.).
By preparing the aqueous ink having the said constituents, even in the case of containing the scaly glittering particles with the said parameters having quite a large particle size compared with that of the normal coloring pigments, it is capable of controling the dispersal stability of the said particles in the ink and is capable of preventing the sedimentation of the scaly glittering particles. Therefore, even in the case of applying the ink of this invention to the ink for a ball-point pen, for example, it is capable of showing the excellent glittering feeling of the glittering particles and the strong color development of the colorants at a time, while showing the stability and good writing performance since it can prevent the clogging of the glittering particles with the said large particle diameters at the pen tip.
The object of this invention is to provide a glittering aqueous ink having a stronger glittering feeling and spatial effect and better color development than those achieved by an aqueous ink using conventional glittering pigments without losing a glittering feeling.
The other object of this invention is to provide a glittering aqueous ink capable of showing the glittering feeling of the glittering particles and the color development of the colorants at a time, while maintaining the stability and good writing performance of the ink.